Compounds which are no toxic or only slightly toxic against pests, but in combination with active ingredients can give a new product active against pests, having an effectiveness significantly greater than the sum of the components when used separately, are named synergists.
These compounds may in principle act in several ways, but one of the main mechanisms reported in the art is the interaction with the metabolism of the active substance. Metabolism can proceed through oxidative, hydrolytic, conjugative and absorption reactions and possible variations thereof.
On the basis of the discovery of synergists and of their way of actions, a wide range research and development started from the mid 60′, thus giving products that were interesting for scientific research , but only a few for market purposes. One of the most effective and widely used synergists is represented by piperonyl butoxide (5-4[[2-(2-butoxyethoxy)]methyl]-6-propyl-1,3-benzodioxole), claimed in U.S. Pat. No. 2,550,737.
Piperonyl butoxide is claimed to give a synergistic effect in combination with pyrethrins as well as pyrethroids such as allethrin, prallethrin, tetramethrin and so on. Other synergists have been proposed such as MGK 264 (N-2-ethylhexylbicyclo[2.2.1]-5-heptene-2,3-dicarboximide) reported by Moore J. B. in Proceed. Mid-Year Meeting, Chem. Spec. Manuf. Ass.(1950), June, 72. Among different synergists, alkynyl derivatives were cited to give synergistic effect when in composition with pyrethroids or other active ingredients against pests. These alkynyl compounds generally belong to two different families, being the first one represented by phenyl alkynyl ethers and the second one by benzyl alkynyl ethers. Other families can be represented, by instance, by N-(omega-alkynyl)phtalimides as claimed in GB 1,038,693; naphtalenecarboxylic acid esters of alkynyl alcohol as claimed in U.S. Pat. No. 4,291,058 as insecticides and acaricides; oxime alkynyl ethers as claimed in U.S. Pat. No. 3,980,799 as synergists in combination with phosphoric esters, carbamates and pyrethroids. Among the first chemical family (phenyl alkynyl ethers) we can mention phenyl-2-propynyl ethers with a synergistic effects against pests when used in combination with carbamates (Fellig J. in J. Agr. Food. Chem.,18(1), 78-80); U.S. Pat. Nos. 3,423,428 and 3,524,915 which claim methylenedioxy propynyl ethers with a synergistic effect in combination with carbamates; U.S. Pat. No. 3,777,024 which claims aryl propargyl ethers and thioethers as synergists in combination with phosphoric esters, nitrophenols and chlorinated hydrocarbon.
Among the second family (benzyl propynyl ethers) U.S. Pat. No. 3,880,999 can be mentioned, which claims benzyl 2-propynyl ethers to enhance the activity of pyrethroids and phosphoric esters; U.S. Pat. No. 6,277,867, WO1998/22416 and WO1998/22417 which claim benzyl alkynyl ethers as synergists in combination with pyrethroids and carbamates and the process thereof.
Nevertheless all these products didn't satisfy completely the synergistic activities and new synergistic compounds were needed.
The object of the present invention is therefore to provide synergistic compounds having a high activity against pests in combination with different active ingredients.